In an image display device such as a liquid crystal display device, to prevent the image display panel from being damaged and to protect the surface thereof, a transparent protective panel such as a glass panel or a plastic panel is arranged on the front face of the image display panel. More specifically, for example, the protective panel is mounted inside a case with a slight gap with respect to the image display panel, by arranging a spacer or the like between the image display panel and the protective panel at the peripheral edge of the image display panel.
However, when such a configuration is employed, the gap between the image display panel and the protective panel scatters light, resulting in decreased contrast and luminance. This leads to the problem that image quality is harmed. Furthermore, in a configuration in which a gap is present, reflection occurs at the interface between the protective panel and air due to their different refractive indices, which leads to visibility problems, especially outdoors.
Based on such circumstances, it has been proposed to fill a resin between the image display panel and the protective panel. For example, in the liquid crystal display device described in Patent Document 1, a spacer is arranged on the periphery of a polarizing plate which is pasted on the surface of a liquid crystal display panel, and a surface protective glass is mounted on an upper portion of the spacer. Furthermore, the surface protective glass is mounted on the liquid crystal display panel by filling an adhesive so that air bubbles do not enter between the polarizing plate and the surface protective glass.
Patent Document 2 also describes an image display device in which an image display panel and a protective panel are closely adhered via at least one or more layers of a transparent adhesive material. Patent Document 2 describes that excellent impact resistance can be realized by having a predetermined relationship between the thickness of the transparent adhesive material and the dynamic viscoelastic properties measured based on frequency dispersion.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2005-55641
[Patent Document 2] Japanese Patent Application Laid-Open No. 2003-29644